Light controlled delay circuit (1)
Source: InternetPublisher:两手空空 Keywords: Light control delay circuit BSP electric lamp Updated: 2021/08/06
At night, turn off the lights to rest or go outside, and do not allow the darkness to explore around the bed or around the room.
It would be much more convenient if another small lamp could automatically light up for dozens of seconds when the light is turned off . The light-controlled delay lamp
introduced in this example is controlled by indoor light. When there is light in the room, the small lamp will turn
on; when the light in the room suddenly changes from bright to dark, the small lamp will light up and delay for tens of seconds. Finally, it can self-extinguish
, and its circuit is shown in Figure 204.
G.C. , VDl-VD4 and
vs, etc. form a simple power circuit,
which outputs about 12V DC voltage to power the whole machine
. RL is a photoresistor.
When the indoor light is strong, it shows low
voltage H【, c. The trapped charge passes through RI. ,
Vn5 is leaking, VT terminal cannot get the base
bias current and is cut off, relay K does not
operate, and small lamp E does not light up. When the
indoor lights are turned off , the light becomes dim,
RI. Immediately presents a high resistance, (1. It begins to charge through the ruler, R. and VT emitter junction, vr therefore obtains the base
bias current and conducts. The relay K is attracted, its moving contact point kl is closed, and the lighting lamp E is turned on. It emits light when energized.
After tens of seconds, the G charge base is fully charged, and the charging current gradually reduces to zero. The relay K loses power and is released, and
the small lamp E goes out. If the light is turned on for the second time or at dawn in the morning, RL returns to low Level, (1. It can
be discharged through RL, VI)5, and f returns to the original state.
C. Use Cl'iFl-400V polypropylene resistor, RI_ use MG45 type photoresistor, etc., island resistor is required
The larger the difference between the phase difference and the hidden phase, the better. K can use IZC, -22F, DC12V small medium-power electromagnetic relays.
The requirements for other components are as shown in the figure.
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